Environmental Engineering Reference
In-Depth Information
Postconsumption
From the point of view of the analysis of the food supply chain, the last step is the consumer.
However, when examining the environmental impact of the whole food supply chain, an
additional important step needs to be included: postconsumption. Postconsumption
encompasses the disposal of solid waste (i.e., food waste, food scraps, and packaging material)
and liquid waste managed by municipal sewer systems.
Some of the solid waste is recycled with variable rates of success in different countries and
the rest is disposed in sanitary landfills. Trash collection and transportation to landfills are the
most immediate impacts. Later on when landfills are covered and become anaerobic, bacterial
fermentation produces methane, which is a greenhouse gas twenty-one times more powerful
than carbon dioxide. Fortunately modern landfills have the capability of collecting methane
(mixed with other gases) that can be used for energy generation.
The value of recycling is sometimes debated in terms of its net use of energy. However,
recycling saves natural resources and energy to extract those resources, particularly minerals.
Recycled aluminum saves up to 95 percent of energy when compared to primary produced
aluminum (“The truth about recycling,” 2007). As a bonus, recycling aluminum reduces the
emission of the powerful greenhouse gases perfluorocarbons (PFCs) (
see
Table 8.4), which
are released during the electrolytic reduction of alumina (Al
2
O
3
) into aluminum. In the same
way, recycling other materials save energy to different extents (see Table 12.3).
SUMMARY
The food supply chain has significant environmental impacts at every single link of the chain,
which includes production, processing, distribution, consumption, and postconsumption.
Production of food in the fields requires the input of energy, fertilizers, water, and pesticides.
The processing stage uses energy for heat and mechanical operations, vast amounts of water,
and additional materials, such as ingredients and packaging. Processing produces direct and
indirect air emissions as well as liquid effluents, which are rich in high-solid contents that
require treatment with the associated environmental impact. Distribution has the need of
specialized warehouses that require energy for their operation. At the end of the chain, the
impact of consumption and postconsumption depends on consumers' choices, diets, and
shopping habits. Every link of the supply chain is connected by transportation, which consumes
fossil fuels and generates air emissions.
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